1. Field of the Invention
The present invention is directed to an apparatus and method for monitoring, quantifying, and verifying the performance of magnetic auditory prostheses and electromagnetic audio systems. More particularly, the present invention is directed to providing a magnetic-to-acoustic interface for magnetic auditory prostheses and electromagnetic audio systems so that they may be tested and evaluated with techniques as are used in acoustic testing and monitoring.
2. State of the Art
It is known to use hearing aids which provide an acoustic signal in the audible range and in the ultrasonic range to a user in order to modify the auditory characteristics of sound received by the user. Because hearing capabilities are quite different from individual to individual, the acoustic hearing aids must be adjusted to properly compensate for the hearing capability of the individual user. To adjust the acoustic hearing aids for optimum benefit to the user, a so-called xe2x80x9cfittingxe2x80x9d is performed to provide the appropriate auditory characteristics. The fitting process typically involves measuring the auditory characteristics of an individual""s hearing, estimating the acoustic characteristics needed to compensate for the particular auditory deficiency measured, adjusting the auditory characteristics of the acoustic hearing aid so that the appropriate acoustic characteristics may be delivered, and verifying that these particular auditory characteristics do compensate for the hearing deficiency found by operating the acoustic hearing aid in conjunction with the individual. Acoustic hearing aids which store acoustic parameters and are programmable by a host computer or a programming device are also known. Standard techniques are known for these fittings which are typically performed by an audiologist, hearing aid dispenser, otologist, otolaryngologist, or other doctor or medical specialist.
Another type of known auditory prostheses utilizes electromagnetic energy to vibrate the middle ear structures or the tympanic membrane, a so-called xe2x80x9cmagnetic hearing aid system.xe2x80x9d A small magnet may either be placed on the structures or membrane or attached to the structures or membrane by a surgical procedure or with an adhesive. An electromagnetic coil is then placed inside or outside of the external auditory canal for producing electromagnetic fields which vibrate the magnet. As a result, the ear structures are vibrated to produce the sensation of enhanced hearing to the user of the magnetic hearing aid system. Examples of such magnetic hearing aid and electromagnetic audio systems are described in U.S. Pat. No. 4,957,478 to Maniglia, U.S. Pat. No. 5,259,032 to Perkins et al., and U.S. Pat. No. 5,425,104 to Shennib.
Magnetic hearing aid systems produce electromagnetic energy from electrical signals rather than acoustic energy as is produced in the acoustic hearing aids. Because the electromagnetic energy has the same amplitude and frequency variation characteristics as the driving electric signal, audible sounds of the same characteristics as the original source signals are produced from vibrations of the magnet placed on the inner ear structure which are induced by the electromagnetic fields. Therefore, a problem exists with these magnetic hearing aid systems because an acoustic signal is not generated. As a result, conventional acoustic fitting equipment and procedures cannot be used to monitor and verify the performance of these electromagnetic audio systems. For instance, even a simple listening check of the magnetic hearing aid system cannot be conducted because the magnetic hearing aid systems do not produce an acoustic output. Also, when manufacturing magnetic hearing aid systems, it is necessary to perform production testing, similar to tests performed in the fitting process, to ensure that the systems meet the required specifications before shipping.
In addition, the performance of the electromagnetic audio systems cannot be evaluated with standard acoustic couplers because these standard acoustic couplers are not designed to respond to electromagnetic energy. Therefore, apparatus and techniques are desired for monitoring, quantifying and verifying the functioning of electromagnetic audio systems. One way to accomplish this monitoring, quantifying, and verifying would be to design completely new equipment and procedures for these electromagnetic audio systems. However, such an approach is very costly and would introduce new and additional equipment and procedures that are unfamiliar to the audiologist or fitter of the magnetic hearing aid systems which undesirably requires new training and more laboratory space. Accordingly, procedures are desired for monitoring, quantifying, and verifying magnetic audio systems so that additional training, costs and equipment for monitoring, quantifying, and verifying magnetic audio systems are minimized, which preferably makes use of conventional acoustic testing techniques.
The present invention is directed to an apparatus and method for monitoring, quantifying, and verifying the operation of electromagnetic audio systems. Because electromagnetic audio systems do not have an acoustic output, conventional acoustic hearing aid test systems as presently configured cannot be used to monitor electromagnetic audio systems. This invention allows electromagnetic audio systems to interface with commercial acoustic hearing aid test systems so that known acoustic procedures and equipment may be used to monitor, quantify, and verify the performance of electromagnetic audio systems.
More particularly, the present invention monitors electromagnetic audio systems by disposing the electromagnetic audio system in an acoustic hearing aid testing device and then detecting the magnetic field output by the electromagnetic audio system with a magnetic-to-acoustic converter when the electromagnetic audio system is being tested by the acoustic hearing aid testing device. The magnetic-to-acoustic converter then develops an acoustic output signal representative of the detected magnetic field which may then be used in traditional qualitative and quantitative acoustic monitoring techniques, such as performing a listening check of the electromagnetic audio system or performing standardized measurements, by the audiologist or tester. Also, presently available commercial acoustic hearing aid testing devices such as Frye Fonix, Rastronics, Acoustimed, AudioScan, BandK, Interacoustics, Madsen, Saico, or Sarffa electroacoustic hearing aid analyzers may be used to monitor, quantify, and verify the performance of electromagnetic audio systems.